Locomotory Appendages of Trilobites. 203 
cases two centimeters in length and quite large, with the mero-carpopo- 
dite articulation well pronounced, so as to leave a distinct, pit-like 
depression in the matrix. The several joints externally to that which 
is considered the meropodite can be distinguished by careful study of 
the several legs and the grooves and fovez of the matrix. The car- 
popodite was about the length of the meropodite, but decidedly slender 
as compared with the latter. If there was any positive evidence to 
show that these were broad, lamellar appendages, adapted to swim- 
ming, then the slender joints external to the meropodite might be. 
accounted for by supposing the edges were the portions visible. The 
propodite was about two thirds the length of the carpopodite, and 
also appears to have been slender and slightly curved backward; the 
dactylopodites are not well preserved, yet sufficiently so to permit the 
conclusion that they were not chelate. The posterior pair of these 
thoracic appendages is directly beneath the posterior somite of the 
thorax. The meropodites of the two anterior pairs of appendages, as 
shown in fig. 3, resemble the same joints in the thoracic limbs. 
In examining the matrix, fig. 3, d, where the left limb of the anterior 
pair is well preserved, it is seen to curve around the outer margin of the 
left lobe of the hypostoma, and from the evidence which the surface pre- 
sented when first examined, I am of the opinion that this limb was 
chelate. In removing the limestone so as to expose the left lobe of the 
hypostoma, and also establish the articulation of the claws, an acci- 
dental stroke destroyed the evidence of this direct connection, yet at 
the fracture the ends of two broken claws can yet be seen. At first I 
was disinclined to regard the distal extremity of this pair as chelate. 
Before attempting to remove the limestone, the surface clearly showed 
a conjunction of these parts. This condition could have been ac: 
counted for by supposing one limb to have been thrown over another. 
It was to clear up this point that the removal of the adhering material 
was made. If chelate, the claws were:slender and of about equal size 
asin Limulus. As the hypostoma is frequently found in this limestone 
formation, it is to be hoped that these limbs will also be found, so as 
to definitely settle this point. On fitting the two specimens together, 
the ends of these supposed claws are seen at the fracture directly be- 
neath the left eye. These specimens demonstrate that the thoracic ap- 
pendages were well developed, walking legs extending nearly to the 
outer margins of the carapace. The exoskeleton of the limbs seems to 
have been somewhat different in character from the calcareous exoskele- 
ton of the dorsal surface of the animal. At least, it was of such a 
character as not to preserve well the integrity of the parts in the pro- 
cess of fossilization. They could not have been soft and yielding, judg- 
